On Fri, Jul 15, 2016 at 2:42 PM, Jakub Jelinek <ja...@redhat.com> wrote: > While in C++11, builtins returning two results, one of them by dereferencing > a pointer argument can't be constexpr, in my understanding in C++14 > generalized constexprs they can.
Yes. > So, this patch tweaks cxx_eval_builtin_function_call so that it handles how > builtins.c folds these builtins (i.e. COMPOUND_EXPR with first operand > being *arg = const1 and second operand const2, optionally all wrapped into a > NON_LVALUE_EXPR. Why so specific? Can't we just pass the return value from fold into cxx_eval_constant_expression, if it isn't still a CALL_EXPR? Incidentally, I think we should be using fold_builtin_call_array rather than fold_build_call_array_loc. > In addition, I've noticed that the lval argument is passed down to > evaluation of arguments, that doesn't make sense to me, IMHO arguments > should be always evaluated as rvalues (and for non-builtins they are). I'm a bit nervous about this, since some builtins take arguments by magic rather than by value, but I'm willing to accept this and see what breaks. Jason
